This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Recent experiments demonstrate close interaction between cartilage and bone compartment in vitro and in vivo, where bone cells from OA patients can cause matrix breakdown of articular cartilage and interruption of contact with subchondral bone results in cartilage degeneration. However, the communication pathway that allows cartilage and bone to interact is not clear. Dr. Wang has recently developed a method based on Fluorescence Recovery After Photobleaching (FRAP) which allows direct measurement of solute movement in the bone in situ and in real time. Drs. Wang et al. propose to use this approach in combination with mathematical modeling to characterize the solute diffusivity of representative molecules through subchondral bone plate in normal and OA joints. This project will build upon the biological foundation of project #1. Dr. Duncan will serve as mentor.